1. Field of the Invention
This invention relates to an electrolyte for driving electrolytic capacitors and also to capacitors using the electrolyte.
2. Description of the Prior Art
A typical known electrolyte used for driving an electrolytic capacitor is one which is obtained by dissolving ammonium adipate solute in a solvent mainly composed of ethylene glycol. This electrolyte is disadvantageous in low specific conductance and a great variation in the conductance at high temperatures.
In order to overcome the disadvantage, Japanese Laid-open Patent Application No. 59-78522 describes an electrolyte for driving electrolytic capacitor which has high specific conductance. This electrolyte is a solution of a quaternary ammonium salt of dibasic carboxylic acid of the formula, HOOC--(CH.sub.2).sub.n --COOH, wherein 4.ltoreq.n.ltoreq.8, dissolved in a mixed solvent of a dipolar organic solvent and from 2 to 10 wt % of water.
Moreover, Japanese Laid-open Patent Application No. 62-248217 describes an electrolyte for electrolytic capacitor which has high specific conductance and is stable at high temperatures. The electrolyte is made of a quaternary ammonium slat of aliphatic saturated dicarboxylic acid dissolved in a solvent mainly composed of .gamma.-butyrolactone.
However, these electrolytes make use of solvents mainly composed of N,N-dimethylacetamide or .gamma.-butyrolactone, which are high in vapor pressure. This leads to a high vapor pressure of the electrolyte, with the result that when such an electrolyte is used to drive capacitor, an amount of the electrolyte which passes through a sealed portion such as with rubber and evaporates to outside becomes larger than known electrolytes. This presents the problem that the actual life of the electrolytic capacitor is not improved as desired.